-- `intellitab.nvim` by Pedro Alves (https://github.com/pta2002)
-- URL: https://github.com/pta2002/intellitab.nvim?tab=MIT-1-ov-file
-- Copyright 2021 Pedro Alves. Licensed under MIT.

local v = vim.api

local treesitter = require("nvim-treesitter")

local function get_line_indent(line, sw)
	local indent = 0

	for c in line:gmatch("%s") do
		if c == "\t" then
			indent = indent + sw
		else
			indent = indent + 1
		end
	end

	return indent
end

local function indent()
	local cursor = v.nvim_win_get_cursor(0)
	local line = v.nvim_buf_get_lines(0, cursor[1] - 1, cursor[1], false)[1]

	local indentexpr = v.nvim_buf_get_option(0, "indentexpr")
	local expand = v.nvim_buf_get_option(0, "expandtab")
	local shiftwidth = v.nvim_eval("shiftwidth()")
	local tab_char = v.nvim_replace_termcodes("<Tab>", true, true, true)
	local indent_goal

	if treesitter ~= nil and treesitter.get_indent ~= nil then
		indent_goal = treesitter.get_indent(line)
	end

	if indent_goal == nil or indent_goal < 0 then
		if indentexpr ~= "" then
			indent_goal = v.nvim_eval(indentexpr)
		elseif v.nvim_buf_get_option(0, "cindent") then
			indent_goal = v.nvim_call_function("cindent", { cursor[1] })
		else
			indent_goal = v.nvim_call_function("indent", { cursor[1] })
		end
	end

	if indent_goal == -1 and cursor[1] ~= 1 then
		local prev_line = v.nvim_buf_get_lines(0, cursor[1] - 2, cursor[1] - 1, false)[1]
		indent_goal = get_line_indent(prev_line, shiftwidth)
	end

	-- Reset the cursor, since the functions are free to move it
	v.nvim_win_set_cursor(0, cursor)

	if cursor[2] == 0 and line == "" and indent_goal ~= nil and indent_goal > 0 then
		local i = 0
		while i < indent_goal do
			if expand then
				v.nvim_feedkeys(" ", "n", true)
				i = i + 1
			else
				v.nvim_feedkeys(tab_char, "n", true)
				i = i + shiftwidth
			end
		end
		print(i, indent_goal)
	else
		v.nvim_feedkeys(tab_char, "n", true)
	end
end

return { indent = indent }